1. Field of the Invention
The present invention relates generally to methods for forming isolation regions within semiconductor substrates. More particularly, the present invention relates to local oxidation of silicon (LOCOS) methods for forming silicon oxide isolation regions within silicon semiconductor substrates.
2. Description of the Related Art
Semiconductor integrated circuit microelectronic fabrications are formed from semiconductor substrates within an upon which are formed semiconductor devices and over which are formed patterned conductor layers which are separated by dielectric layers.
In the process of fabricating semiconductor devices within and upon semiconductor substrates employed within semiconductor integrated circuit microelectronic fabrications, it is common in the art of semiconductor integrated circuit microelectronic fabrication to first form within a semiconductor substrate within which is desired to form a series of semiconductor devices a series of isolation regions for purposes of isolating the series of semiconductor devices such as to reduce detrimental effects, such as but not limited to detrimental parasitic effects and detrimental cross-talk effects, when operating a semiconductor integrated circuit microelectronic fabrication formed from the semiconductor substrate having formed therein the semiconductor devices. Of the types of isolation regions which may be employed when fabricating semiconductor integrated circuit microelectronic fabrications, silicon oxide isolation regions formed employing local oxidation of silicon (LOCOS) thermal oxidation methods are particularly common in the art of silicon semiconductor integrated circuit microelectronic fabrication.
While local oxidation of silicon (LOCOS) methods for forming silicon oxide isolation regions within and upon silicon semiconductor substrates are thus clearly desirable in the art of silicon semiconductor integrated circuit microelectronic fabrication and often essential within the art of silicon semiconductor integrated circuit microelectronic fabrication, local oxidation of silicon (LOCOS) methods for forming silicon oxide isolation regions within and upon silicon semiconductor substrates are nonetheless not entirely without problems in the art of silicon semiconductor integrated circuit microelectronic fabrication. In that regard, it is known in the art of silicon semiconductor integrated circuit microelectronic fabrication that when forming silicon oxide isolation regions while employing local oxidation of silicon (LOCOS) methods there is often formed beneath a local oxidation of silicon (LOCOS) oxidation mask layer a bird""s beak extension of a silicon oxide isolation region. The bird""s beak extension of the silicon oxide isolation region in turn generally compromises an areal dimension of an active region of a semiconductor substrate which is bounded by the silicon oxide isolation region.
It is thus desirable in the art of silicon semiconductor integrated circuit microelectronic fabrication to provide methods and materials which may be employed for forming, with attenuated bird""s beak extensions, silicon oxide isolation regions within silicon semiconductor substrates employed within silicon semiconductor integrated circuit microelectronic fabrications.
It is towards the foregoing object that the present invention is directed.
Various methods and materials have been disclosed in the art of silicon semiconductor integrated circuit microelectronic fabrication for forming, with desirable properties, silicon containing structures within silicon semiconductor integrated circuit microelectronic fabrications.
Included among the methods and materials, but not limiting among the methods and materials, are methods and materials disclosed within: (1) Pfiester et al., in U.S. Pat. No. 4,728,619 (an ion implant method which employs a germanium ion implant material in conjunction with a boron ion implant material or a phosphorus ion implant material for purposes of controlling the dimensions of a boron ion implant channel stop structure or a phosphorus ion implant channel stop structure within a silicon semiconductor substrate employed within a silicon semiconductor integrated circuit microelectronic fabrication when forming while employing a local oxidation of silicon (LOCOS) method a silicon oxide isolation region within the silicon semiconductor substrate); and (2) Chang et al., in U.S. Pat. No. 6,030,863 and U.S. Pat. No. 6,037,204 (an ion implant method which employs in an alternative a germanium and arsenic ion implant material or a silicon and arsenic ion implant material for preamorphizing a silicon layer within a silicon semiconductor integrated circuit microelectronic fabrication prior to forming thereupon a metal silicide layer while employing a thermal annealing method within the silicon semiconductor integrated circuit microelectronic fabrication).
Desirable in the art of silicon semiconductor integrated circuit microelectronic fabrication are additional methods and materials which may be employed for forming within silicon semiconductor substrates, and while employing local oxidation of silicon (LOCOS) methods, silicon oxide isolation regions with attenuated bird""s beak extensions.
It is towards the foregoing object that the present invention is directed.
A first object of the present invention is to provide a local oxidation of silicon (LOCOS) method for forming a silicon oxide isolation region within a silicon semiconductor substrate.
A second object of the present invention is to provide a local oxidation of silicon (LOCOS) method in accord with the first object of the present invention, wherein the silicon oxide isolation region is formed with an attenuated bird""s beak extension.
A third object of the present invention is to provide a location oxidation of silicon (LOCOS) method in accord with the first object of the present invention and the second object of the present invention, wherein the method is readily commercially implemented.
In accord with the objects of the present invention, there is provided by the present invention a local oxidation of silicon (LOCOS) method for forming a silicon oxide isolation region within a silicon semiconductor substrate.
To practice the method of the present invention, there is first provided a silicon semiconductor substrate. There is then formed over the silicon semiconductor substrate an oxidation mask layer which leaves uncovered an isolation region location within the silicon semiconductor substrate. There is then implanted into the isolation region location, while employing the oxidation mask layer as an ion implantation mask layer, a dose of an amorphizing ion which amorphizes areally completely at least a surface sub-layer portion of the silicon semiconductor substrate within the isolation region location to form an amorphized silicon region within the isolation region location. Finally, there is then thermally oxidized the silicon semiconductor substrate having formed thereover the oxidation mask layer to form at least in part from the amorphized silicon region a silicon oxide isolation region.
In a more general sense, the present invention also provides a local oxidation of silicon (LOCOS) method for forming within a microelectronic fabrication an isolation region adjoining a silicon layer formed from a silicon material selected from the group consisting of monocrystalline silicon materials and polycrystalline silicon materials, with an attenuated bird""s beak extension of the isolation region.
In a more specific sense, the present invention also provides particular value within the context of forming, while employing a local oxidation of silicon (LOCOS) method, an isolation region defining at least in part an active region of a silicon surface layer within a silicon on insulator silicon semiconductor substrate.
There is provided by the present invention a local oxidation of silicon (LOCOS) method for forming a silicon oxide isolation region within a silicon semiconductor substrate, wherein the silicon oxide isolation region is formed with an attenuated bird""s beak extension.
The present invention realizes the foregoing object by implanting into an isolation region location within a silicon semiconductor substrate having formed thereover an oxidation mask layer, and while employing the oxidation mask layer as an ion implantation mask layer, a dose of an amorphizing ion which amorphizes areally completely at least a surface sub-layer portion of the silicon semiconductor substrate within the isolation region location not covered by the oxidation mask layer, to form an amorphized silicon region within the isolation region location. Thus, when subsequently thermally oxidizing the silicon semiconductor substrate having formed thereover the oxidation mask layer to form at least in part from the amorphized silicon region a silicon oxide isolation region, the silicon oxide isolation region is formed with an attenuated bird""s beak extension insofar as an amorphized silicon material within the amorphized silicon region is thermally oxidized more rapidly than a non-amorphized silicon material, such as in particular a monocrystalline silicon material, from which is formed the silicon semiconductor substrate.
The method of the present invention is readily commercially implemented.
The present invention employs methods and materials as are generally conventional in the art of semiconductor integrated circuit microelectronic fabrication, but employed within the context of a specific process ordering and with a series of specific process limitations to provide the present invention. Since it is thus at least in part a specific process ordering and a series of specific process limitations which provides at least in part the present invention, rather than the existence of methods and materials which provides the present invention, the method of the present invention is readily commercially implemented.